First of all, ACT records at the first instance of damage aka the pull.
The parse you shown had a total raid dps of 1717.16, unless I made a mistake adding somewhere. You can check your self by clicking on the encounter. I just added it up.Here is one of some other group of people with total raid dps of 1773,
http://puu.sh/aaiWa/f168d001b9.png You can notice that it's merged with a total encounter time of 9:31 seconds. What you are telling people right now is that your group manages to kill the same boss like 1 minute faster than a group with a higher total dps since theirs is merged and yours is apparently not.
In comparison, bluegarter kills it in like 10:15 or something.